Health-related quality of life measures are important outcome indicators in clinical trials of healthcare interventions and in evaluations of public health programs. There has been growing interest in utility (preference-based) measures of health-related quality of life. A utility measure provides a single summary score reflecting the value of a health state where 0.00 represents dead and 1.00 is perfect health. These measures permit the integration of mortality and morbidity to summarize population health and are crucial in economic evaluations. However, there are few (if any) long-term studies examining changes in health utility over time in large populations. Consequently, there is little prospective information about aging and utility. Moreover, it is unclear if changes over time in utility are similar to or different from changes over time in widely available measures such as self-rated health. In addition, there are uncertainties about the changes over time in health domains (e.g., pain) that contribute to health utility. Also, and importantly, the impacts on utility of major risk factors for mortality (such as smoking or obesity) have yet to be examined longitudinally. The proposed project will address these issues using ten years of follow-up data on quality of life measured by the Health Utilities Index Mark 3 (HUI3). In the last decade, HUI3 has come into widespread use as a multidimensional measure of health-related quality of life. HUI3 assesses eight domains: vision, hearing, speech, ambulation, dexterity, emotion, cognition, and pain. The index uses population-based preferences to combine the several domains into a single-dimensional weighted average consistent with the requirements for a utility measure. The proposed longitudinal secondary data analysis project will (a) examine change over time in the HUI3 (and its components) across the life course, (b) conduct similar examinations of change over time in self-rated health, (c) investigate predictors of change over time in HUI3, and (d) compare HUI3 scores between Canada and the United States. The project will utilize the Canadian National Population Health Survey which contains ten years of follow-up interviews including HUI3 measures every other year and the 2003 Joint Canada-United States Survey of Health. The project will lay the foundations for future work in which medical and public health interventions (such as risk factor reduction programs) are evaluated according to their impact on health-related quality of life. [unreadable] [unreadable]